Heterocyclization Reactions of Conjugated Heterocumulenes. Synthesis of Pyridine Derivatives by a Tandem Aza Wittig/Electrocyclization Strategy | Zendy

Molina Pedro | Zendy; Arques Antonio | Zendy; Fresneda Pilar M. | Zendy; Vinader Maria Victoria | Zendy; De La Concepciòn FocesFoces Maria | Zendy; Cano Félix Hernandez | Zendy

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Heterocyclization Reactions of Conjugated Heterocumulenes. Synthesis of Pyridine Derivatives by a Tandem Aza Wittig/Electrocyclization Strategy

Author(s) -

Molina Pedro,

Arques Antonio,

Fresneda Pilar M.,

Vinader Maria Victoria,

De La Concepciòn FocesFoces Maria,

Cano Félix Hernandez

Publication year - 1989

Publication title -

chemische berichte

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.667

H-Index - 136

eISSN - 1099-0682

pISSN - 0009-2940

DOI - 10.1002/cber.19891220217

Subject(s) - chemistry , nitromethane , conjugated system , wittig reaction , electrocyclic reaction , pyridine , acetone , molar ratio , medicinal chemistry , ylide , tandem , ring (chemistry) , organic chemistry , catalysis , materials science , composite material , polymer

The aza Wittig reaction of iminophosphorane 3 with isocyanates leads to conjugated carbodiimides 4 , which undergo electrocyclic ring closure to give ethyl 2‐pyridinecarboxylates 5 . Iminophosphorane 9 reacts with nitromethane and acetone in a 1:1 molar ratio to form 10 and 11 , respectively. Reaction of 9 with nitromethane in 1:3 molar ratio yields the iminophosphorane 12 . The structure of 12 has been established by X‐ray crystallography. Iminophosphoranes 10 and 11 react with isocyanates or carbon dioxide to give the pyrazolo[3,4‐ b ]pyridines 13 , 15 and 14 , 16 , respectively.

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